1. Field of the Invention
This invention relates to a dome switch having multiple switching function.
2. Description of the Related Art
A two-step switch is used frequently for a window regulator switch in a car. The first step switch operation, pushed by a finger with click feeling, makes a window glass moved and if the finger is left from the switch on the condition, the window glass is stopped. However, when pushing the switch more over the first step switch operation, the window glass moves continuously until reaching to a specified position (top end or bottom end) even if the finger is left from the switch.
Such two-step switch is usually constituted with combining at least two single switches. An example of a rocker-type combined switch, applied by the two-step switch (example of two rocker-type combined switches mounted on) is shown in FIGS. 12, 13A, 13B and 13C.
FIG. 12 is an exploded perspective view of the switch. FIGS. 13A, 13B and 13C are sectional views of one two-step switch for describing its actions.
A switch-operating portion 82, mounted on a cover 81, is pivoted on a shaft 83 capably of rocking. The switch-operating portion 82 is provided inside thereof with cam portions 82a, 82axe2x80x2 for moving pins 82b, 82bxe2x80x2 up and down by rocking the switch-operating portion 82. The switch-operating portion 82 is provided at the back side thereof near the cam portions 82a, 82axe2x80x2 with a concave cam portion 82c for returning the switch-operating portion 82 to a neutral position (position shown in FIG. 13A), which is in a condition of OFF (electrically nonconductive condition) on single switches 87, 87xe2x80x2, by combined action of the concave cam 82, a restraining pin 84 and a spring 84a when an operator finger is left from the switch-operating portion 82.
An electric circuit body 85, covered by a cover 81, is generally provided with an electric circuit (not shown) and an electric contact. A rubber contact 86 is fixed by a rubber contact locking hole 85a of the electric circuit body and a locking piece 86a of the rubber contact 86.
When single switches 87, 87xe2x80x2, 88 and 88xe2x80x2, mounted on positions corresponding to contacts for rubber contacts on the electric circuit body 86, are pushed and deformed, electrodes provided at the side of the electric circuit body 85 on the single switches contact respectively with the contacts of the electric circuit body 85 and then the switches turn ON to be electric conductive.
The single switches 87 (87xe2x80x2) and 88 (88xe2x80x2) have deferent stroke length to contact with the electric contacts.
When an operator pushes an arrow portion of the switch-operating portion 82, shown in FIG. 13A, the switch-operating portion 82 sways to be in a condition shown in FIG. 2B. In the condition, a pin 82b is pushed down by the cam 82a and a single switch 87 is pushed so that a first contact (not shown) in the electric circuit body 85 turns ON to be electric conductive. The operator can perceive the single switch 87 turning ON by operation feeling of deformation of a rubber portion of the single switch 87.
When the operator pushes down more the switch-operating portion 82, the switch-operating portion 82 sways more to be in a condition shown in FIG. 13C. In the condition, not only the single switch 87 but also the single switch 88 turn ON to be electric conductive.
After that, when the operator moves the finger away from the switch-operating portion 82, the switch-operating portion 82 returns to a neutral position (position shown in FIG. 13A and the single switches 87, 88 turn OFF.
Thus, operating a left side (an arrow portion) of the switch-operating portion 82, three conditions which are both single switches 87, 88 OFF (OFF+OFF), only single switch 87 ON (ON+OFF) and both single switches 87, 88 ON (ON+ON) can be given to control various operations with relays or control circuits sensing conditions of single switches.
Describing above the example of operating the left side in a figure of the switch-operating portion 82, in case of operating a right side of the switch-operating portion 82, firstly a single switch 87xe2x80x2 turns ON and secondly a single switch 88xe2x80x2 turns ON.
In such two-step switch, a rubber contact locking piece projects from a rear surface of an electric circuit body to be an obstacle to mount the electric circuit body on a surface in an equipment with a double-side adhesive tape or the like. Therefore, getting watertight structure is hindered and also getting thinner thickness of a single switch portion becomes difficult. Two respective single switches are required to have three conditions which are OFF+OFF, ON+OFF and ON+ON so that miniaturization of the single switch is difficult.
In a process from the first step to the second step, a reaction force by compressive elasticity of a rubber portion of the single switch 87 is relative strong to be difficult to sense securely the operation of the switch-operating portion by only operating feeling when the two single switches turn ON.
Objects to be Solved
This invention has been accomplished to overcome the above drawbacks and an object of this invention is to provide a switch having multiple switching functions to be easily miniaturized, watertight and compact.
How to Attain the Object
In order to attain the objects, according to an aspect of this invention, there is provided a dome switch including a single switch comprising a front sheet having a domed projection projecting outside, being reversed to a back side and provided at the back side with an electrode; an electric circuit body having an electric contact to contact with an electrode provided on the domed projection when the domed projection is turned over; and a domed convex portion provided near the center of the domed projection. In process of pushing the convex portion, firstly the projection is turned over and an electrode provided near the periphery of the convex portion at the back side of the front sheet contacts with the electric contact provided on the electric circuit body and secondly an electrode provided near the center of the domed convex portion at the back side of the front sheet contacts with the electric contact provided on said electric circuit body.
In the above-mentioned structure, the dome switch can be thinner and more compact and water-tighten easily. Furthermore, any locking piece provided on a back side of the electric circuit body is not required, then the dome switch can be mounted easily on a surface of an equipment.
According to an other aspect of the invention, there is provided the dome switch which comprises the dome switch as referred to above, wherein the domed convex portion has a structure capable to turn over to the back side of the front sheet. In the above-mentioned structure, an operator can confirm an action of a second step switch by feeling and then more secure operation can be done.
According to further aspect of the invention, there is provided the dome switch which comprises the dome switch as referred to above, and has a plurality of the single switches. In the above-mentioned structure, more complicated function and operation can be given to keep compact size.
According to a more other aspect of the invention, there is provided the dome switch which comprises the dome switch as referred to above all, and is provided between the front sheet and the electric circuit body with a spacer sheet formed with a throughhole for ensuring contact between the electrode at the back side of the front sheet and the electric contact of the electric circuit body in the single switch to prevent deformation of the front sheet.
In the above-mentioned structure, deformation of the front sheet is prevented for a lot of repeat operation so that durability and reliability of the switch are extremely improved.
According to a further aspect of the invention, there is provided the dome switch which comprises the dome switch as referred to above, wherein the spacer sheet functions to provide a stroke distance for the projection and the convex portion.
In the above-mentioned structure, a depth of the throughhole can be increased and then the stroke distance for the projection can be increased. Thus, the spacer sheet functions to provide a large stroke distance for the projection.
According to a further aspect of the invention, there is provided the dome switch which comprises the dome switch as referred to above, wherein the spacer sheet includes multi-layered sheets and a top layered spacer sheet at the front sheet side is formed thinner than other under layered spacer sheet for fine adjustment of the stroke distance.
In the above-mentioned structure, total thickness of the spacer sheets can be adjusted by number of layers and the stroke distance of the projection can be easily adjusted and fine adjusting can be done.
Further, forming a spacer sheet with multi-layered sheets, stiffness of the spacer sheet becomes more flexible than that of a single-layered sheet.
According to a further aspect of the invention, there is provided the dome switch which comprises the dome switch as referred to above, wherein a diameter of the throughhole of the top layered spacer sheet is formed larger than or equal to a diameter of the projection, and a diameter of the throughhole of the under layered sheet is formed larger than or equal to the diameter of the top layered sheet.
In the above-mentioned structure, deformation of the front sheet, around the throughhole, by turning the projection over can be minimized and then durability and reliability of the front sheet are extremely improved.
According to a further aspect of the invention, there is provided the dome switch which comprises the dome switch as referred to above; a plurality of the single switches; a spacer sheet being formed in positions corresponding to the plurality of the single switches with throughholes for ensuring contact between the electrode at back side of the front sheet and the electric contact of the electric circuit body in each of the single switches to prevent the front sheet from deformation, and located between the front sheet and the electric circuit body; and an air communicating portion for communicating the throughholes in the spacer sheet with each other.
In the above-mentioned structure, various operations with the plurality of single switches can be done and increasing air pressure in a corresponding throughhole of the spacer sheet by operating a single switch can be released to other throughhole for other single switch. Therefore, deterioration of operation feeling and water-tightness by air pressure increasing can be prevented and durability of the switch can be improved.
According to a further aspect of the invention, there is provided the dome switch which comprises the dome switch as referred to above, wherein the spacer sheet includes multi-layered sheets and the air communicating portion is provided on the spacer sheet other than a top layered spacer sheet at the front sheet side.
In the above-mentioned structure, deterioration of the front sheet by an edge of the air communicating portion can be prevented and durability and reliability of the switch can be improved.
According to a further aspect of the invention, there is provided the dome switch which comprises the dome switch as referred to above, an adhesive layer provided on a rear surface of the electric circuit body for fixing the dome switch on a mounting device, and an air vent through the electric circuit body and the adhesive layer being communicated with the air communicating portion.
In the above-mentioned structure, providing an airtight air chamber on an area, corresponding to the air vent of the adhesive layer, of the mounting device mounted with the dome switch, deterioration of operation feeling on a single switch can be prevented almost completely.
According to a further aspect of the invention, there is provided the dome switch which comprises the dome switch as referred to above, wherein a light emitting diode is mounted on a front sheet side surface of the electric circuit body, wherein the spacer sheet is provided with a light guide portion for receiving said light emitting diode and guiding a light of the diode to the front sheet, and wherein the front sheet has a light transmissible area which corresponds to said light guide portion and illuminated by the light emitting diode (LED is short form after this).
In the above-mentioned structure, an LED mounted on an electric circuit body in a dome switch assembly can be received in a light guiding portion of a spacer sheet and then LED can be mounted on a front sheet side surface of the electric circuit body. A light, emitted by the LED mounted on an electric circuit body, is guided through the light guiding portion of the spacer sheet and then a lighting area of the front sheet is illuminated. The light through the lighting area makes lighting area look just as if the lighting area emits by itself.
According to a further aspect of the invention, there is provided the dome switch which comprises the dome switch as referred to above, wherein a light diffusing device is provided between the light guiding portion and the lighting area.
In the above-mentioned structure, a lighting area of a front sheet is illuminated by diffused light by a light diffusing device when an LED is emitted. Therefore, partial lighting (non-uniformity) is prevented so that high grade looking can be given.
According to a further aspect of the invention, there is provided the dome switch which comprises the dome switch as referred to above, wherein a chip-type component is mounted on a front sheet side surface of the electric circuit body and the spacer sheet has a chip type component receiving section for receiving the chip type component.
In the above-mentioned structure, a chip-type component can be mounted on a front sheet side surface of the electric circuit body.
According to a further aspect of the invention, there is provided the dome switch which comprises the dome switch as referred to above, wherein the front sheet has a projection in a location corresponding to the chip type component receiving section of the spacer sheet.
In the above-mentioned structure, a chip-type component, higher than a thickness of a spacer sheet, can be mounted if a chip-type component is mounted on a front sheet side surface of the electric circuit body. Therefore, a thicker spacer sheet affecting operating feeling of a single switch is not required to mount a higher chip type component.
According to a further aspect of the invention, there is provided the dome switch which comprises the dome switch as referred to above all, wherein the electric circuit body is provided, on a rear surface thereof, with an adhesive layer for fixing a dome switch on a mounting device and a chip-type component is mounted on the rear surface of the electric circuit body and the adhesive layer is provided with a chip-type component receiving section corresponding to the chip component.
In the above-mentioned structure, a chip-type component can be mounted on a rear surface of the electric circuit body. Providing a receiving recess in a location corresponding to the chip-type component on the mounting member, flat looking mounting can be done.
According to a further aspect of the invention, there is provided the dome switch which comprises the dome switch as referred to above, wherein the electric circuit body is provide therethrough with an air vent communicating from a space, formed with a domed projection and the electric circuit body, to a rear surface of the electric circuit body.
In the above-mentioned structure, deterioration of operation feeling on a single switch by air in a space, formed with a domed projection and the electric circuit body, can be prevented and the switch can be operated securely.
According to a further aspect of the invention, there is provided the dome switch which comprises the dome switch as referred to above, wherein the electric circuit body is provided, on a rear surface thereof, with an adhesive layer having an air vent corresponding to the air vent of the electric circuit body for fixing a dome switch on a mounting device.
In the above-mentioned structure, a chip type component can be mounted on the rear surface of the electric circuit body in case of a dome switch with an adhesive layer.
According to a further aspect of the invention, there is provided the dome switch which comprises the dome switch as referred to above, and an operating device having an loading portion which is smaller than the convex portion of the single switch for pushing the convex portion and an operating portion which is larger than the convex portion.
In the above-mentioned structure, without deterioration of operation feeling on the single switch, the switch can be operated easily by not only a fingertip, but also other body part or by fingers worn in gloves.
According to a further aspect of this invention, there is provided a rocker-type combined switch comprising a rocker-type operating portion having two symmetrical shaped pushing portions at both ends thereof, a rocker fulcrum portion supporting the rocker-type operating portion as a rocker fulcrum, and a dome switch having at least one single switch, described in all above, respectively under said two pushing portions, and an actuating pin for actuating respectively each convex portion of the at least one single switch by rocking motion of the rocker-type operating portion, wherein a loading portion of the actuating pin, abutting respectively on each convex portion of the single switches, is smaller than each corresponding convex portion of the single switches and the pushing portions are larger than convex portions of the single switches. Therefore, operating a switch is easy and number of components is minimized and designing an electric circuit body is easy and then a compact and watertight switch can be given easily.
According to a further aspect of this invention, there is provided the rocker-type combined switch which comprises the rocker-type combined switch as referred to above, wherein moving direction of the actuating pin for pushing a convex portion of a single switch is the same as stroke direction of the convex portion of the single switch. Therefore, operating a switch can be done very securely.
A dome switch according to this invention is structured by a single switch comprising a front sheet having a domed projection which projects outside and can turn over to the back side and is provided at the back side thereof with an electrode; an electric circuit body having an electric contact contacting with the electrode provided at the back side of the projection when the domed projection is turned over; and a domed convex portion provided near the center of the domed projection. In process of pushing the convex portion, firstly the projection turns over and an electrode provided near the periphery of the convex portion at the back side of the front sheet contacts with the electric contact provided on the electric circuit body and secondly an electrode provided near the center of the domed convex portion at the back side of the front sheet contacts with the electric contact provided on the electric circuit body. Therefore, the dome switch has a simple and reliable structure and is easily miniaturized, water-tightened and thinned, can be operated securely with click feeling.
Although the present invention has been fully described by way of examples with reference to the accompanying drawings, it is to be noted that various change and modifications can be made with the scope of the present invention.